Preheater apparatus for oil burners



Patented June 3, 1930 UNITED STATES ARTHUR J. BAIRD, OF PORTLAND, OREGONPREHEATER APPARATUS FOR OIL BURNEES Application filed December 10, 1928.

This invention relates to improvements in apparatus for preheating fueloil for maintaining combustion in oil-burning furnaces, and particularlyof the type of apparatus described and claimed in my prior patentapplication Serial No. 229,145), filed October 27, 1927.

The principal object of my invention is to provide simple andself-regulatory apparatus tor heating fuel oil preparatory to itsinjection into a furnace and to maintain the temperature of the oilabove a predetermined minimum whereat the oil atomization is productiveoi most eflicient results in combustion.

A further object or" the invention is the provision in preheatingapparatus for oil burners 0t steam-heating and electric heating elementsin operative conjunction and whereby the electric heating devices may beutilized prior to the raising of sufiicient steam for heating purposesor when the steam heat fails for any reason, said auxiliary electricheating devices being constantly available automatically under effectivethermostatic controls. v

w A still further object of my invention is the provision in a preheaterfor oil burners of a venting device communicatively connecting theheating chamber wherein the oil is warmer. for delivery to the burnerand the passage for the cold oil into such chamber whereby gasesgenerated in the heating chamber may be withdrawn from the chamher to hemingled with and absorbed by the incoming oil and thus avoiding thedanger of accumulation of gases in the chamber.

Other objects and advantages residing in my invention and objectsrelating to details of construction and relative arrangements of partsthereof will be readily apparent in the course of the detaileddescription to follow.

The accompanying drawings illustrate by 'ay or' example a preferred termof my invention, in which:

Figure l is a View substantially in medial vertical section of anembodiment of my invention with accessory parts thereof shown in sideelevation.

Fig. 2 is a top plan view of the main body Serial. No. 324,902.

of my improved preheater as on line 22 of Fig. 1.

Fig. 3 is a view in side elevation of the invention with the thermalcontrol apparatus removed, and with the lower portion of the preheatershown in section.

Fig. 4 is a view in horizontal section on line st of Fig. l.

i-leterring to said views, the reference numeral 1 indicates a casinghaving a substantially cylindrical heating chamber 2 which is closedatits bottom by a plate 3.

At the upper end the casing is formed with a laterally directedL-eXtension 5 having a discharge chamber 6 therein open to its fullextent from the heating chamber. A discharge-pipe '2' for the heater oilextends through the bottom wall of the extension to near the top thereofwhere its opening 8 for the ingress of the oil is in close proximity tothe top of the chamber 6 so that only the warmest oil in the heating anddischarge chambers will be withdrawn. The discharge pipe iscommunicatively connected to a burner of any type.

Upon the opposite side of the casing a pipe 10 leads from a source ofoil supply under pressure and is communicatively connected with avertically disposed passage 11 formed in the casing wall. The pressureupon said oil supply may be applied by means of a gravitational systemor through a pump, not shown. The oil issuing through the passage 11takes a vertically upward course and passes through a cell 12 formed inthe casing whence the oil flows downwardly through a passage and inletport 15 into the heating chamber adjacent its bottom.

A steam-coil 16 is connected at one end centrally of said bottom platewith a pipe 17 through which the condensations are earried to asteam-trap 18. The opposite end of said coil extends through the upperwall of the casing where it is connected to a feed-pipe 19 extendingfrom a boiler for generating steam, not sh( vn, to which the apparatuspertains-4.

The numeral 20 indicates an. electric heating element of the immersiontype extending, preferably, through the upper wall of the casing andinto the chamber 2 centrally of the steam-coil spirals.

At the upper end of the heating chamber 2 atube 21 extends through theinterior wall 22 separating the chamber from the cell 12 andcommunicatively connects said chamber and cell through its bore 23. Thetube is of relatively small bore and extends to within close proximityof the opposite side wall of the cell and beyond the upper end of thepassage 11 so that oil flowing through the passages and cell cannotreadily pass by way of the tube into the heating chamber. A screw-plug25 is screwed into the easing-wall opposite the tube 21 through whichthe tube may be cleaned it it should become clogged for any reason. Saidplug may be formed with a recess 26 on its inner side into which thetube may extend.

A thermally cont-rolled switch housed in the box 27 is rigidly mountedon the casing through having;- its ther iostatic element 28 extender.horizontally into the discharge chamber 6 along the lower portionthereof and spaced below the opening 8 of the discharge pipe. Saidswitch is adapted to make and break a circuit formed by wires 30 andincluding the heating element 20 whereby current is supplied to theelement as a heating agency for the oil in the heating chamber (hiringsuch times as the temperature Oi the oil therein remains below apredetermined degree of heat for which the switch is set to break thecircuit and as actuated by the thermostat Such temperature atwhieh theswitch is open ated to break the circuit is desirably set at a degree ofheat somewhat less than the heat of the steam supplied to the coil 16 orat about 1. 10 degrees Fahrenheit at which tem 'ierature he oil. istound to atomize at high el'liciency.

A thermometer 31 may be likewise mounted upon the casing and extendedtherethrough in a. heat-responsive element 32 into the discharge chamber6.

The operation of my improved preheating: apparatus may be brieflydescribed as follows With the apparatus assembled in operative conditionas described and illustrated and assuming that the fire is extinguishedin the furnace, as in the "case of starting; the heating plant at thebeginning of a day. the current is turned through the wires 30 as by amanually operated switch, not shown, wh ch will energize the heatingelement to heat the oil in the chamber 2 with which it is in Contact.When the oil is warmed it rises and fills the discharge chamber at thetop of the casing and when suliiciently warmed as determined by thethermometer 31 the oil pump not shown, or other teed or atomisaingagencies requ red to inject the oil into the furnace are actuatedwhereupon the oil is forced through the pipe 7 to the oil-burner underpressure while an equal amount on;

ters through the supply pige and circulated through the pan-sages ll and13 and heated in the chamber 2 where it flows upwardly while beingsubjected to the heat (it the elecic element.

its soos s steanii is raised sulliciently in the boiler to cute the coill6 the heat therel'roni jo ns with the electrically generated heat towarm the oil until the latter reaches the predetermined temperature atwhich the z-iwitch controlled by the thermostat 28 is set to break theelectric circuit whereupon the steani-coil is relied upon to furnish theenire amount o'l heal utilized unless the steam h at in the coil shoualbe insufficient at any time to maintain the oil circulating through thepr enter at or above the prearranged minimum tempo 'ature at which theswitch is set to close the circuit and again energize the heatingelement. Such utilization. ol: the electric heatingelement as anauxiliary heating agency to the steam-coil as well as a preheater maytilit. place frequently during the daily operation of the furnace and inpractice it found that the thermally controlled switch may be reliedupon during the hours when the Furnace is not in operation to maintainth oi l in warm condition during such idle p ls and in readiness foroperation at any time and with a Very small additional consiniririon ofelectric current.

It is found tha the Vapors arising from the heated oil. will sometimesaccumulate in the heating chamber and force the oil back into the supplypipe unti the heating chamber is more or less emptied of oil. This willhappenv principally when the electric heating element is turned on andthe burner is not in use, resulting in a serious obstacle to a propercirculation of the oil in the chamber. To guard against such collectiono'lf gases I have provided the tube 21 forming: a communication betweentl e upper end of the heating chamber 2 and the cell 12 so that anycases formed in the chamber will be carried into the cell. to beabsorbed hvthe incoming: cold oil or in case. the low of oil is stoppedas by closing down the furnace the gases will escape through the supplypipe without danger of emptyi the heating chamber.

he provision of the discharge chamber as an annex to the heating chamberand the location oi the discharge pipe opcnino' rela tive to thethermostatic element through whose action the automatic switch isregulated whereby the oil at the top of the chamher and which is drawnoft at its highest temperature while the thermostat is situated at alower elevation and is surrounded by a strata of cooler oil thuspromoting eiliciency in ensuring that the oil issuing from the upparatus is always warmed to a si'iitable degree and that the act on ofthe thermostat is moderated and the actuation of the switch only takesplace when there is considerable reserve supply of properly heated oil.

WVhile I have described my invention for convenience and brevity asoperative With steam-heating appliances it Will be apparent that theapparatus is equally effective When utilizing hot Water as a source forWarming the oil in the chamber 2 and Which requires only the provisionof the usual pipe connections to the boiler in addition to the appliances shown in place of the steam-trap 18 to establish a returncirculation in a Well understood manner and which is deemed the fullequivalent with the employment of steam and is so intended to apply bothin the description and the claims relating to my improvement.

Having described my invention, What I claim is:

1. A preheater for fuel-oil, comprising a casing having a heatingchamber communicatively connected With a source of oil supply underpressure and a discharge chamber in said casing communicating with theupper end of said heating chamber, a steam-coil in said heating chamber,an electric circuit ineluding a heating element extending int-o saidheating chamber, a discharge pipe arranged to Withdraw oil from near thetop of said discharge chamber, and a thermostatically controlled switchhaving a thermostatic element extending into said discharge chamber atan elevation below the opening into said discharge pipe and adapted tomake or break said circuit in response to changes in temperature of theoil.

2. A preheater for fuel-oil, comprising a casing having a heatingchamber and a discharge chamber opening out of the upper end 'of theheating chamber, an inverted U-shaped supply passage for oil having aported opening into the heating chamber at the lower end thereof, a venttube between the upper end of the heating chamber and said passage to admit of the escape of gases from the heating chamber, a steam-coilextending into said heating chamber, an electric circuit including aheating element extending into said heating chamber, and an electriccircuit breaker included in said circuit thermally controlled by athermostatic element extending into said discharge chamber.

3. A preheater for fuel-oil, including the apparatus described in claim2, together With a discharge pipe in the discharge chamber having itsWithdrawal opening disposed at a higher elevation than the thermostaticelement of the circuit breaker.

i. A preheater for fuel-oil, consisting in a casing having a heatingchamber therein, a steam-coil and an auxiliary electric heating elementextending into said chamber to heat the oil therein, said heatingelement being included in an electric circuit, a circuit breaker in saidcircuit, a thermostatic element extendchamber.

ARTHUR J. BAIRD.

